The initial leg down in bonds came right after the release of the FOMC statement and updated macroeconomic forecasts at 2 PM ET. The FOMC is more optimistic on the economy than before, which means tapering back of bond purchases under the central bank's program of monetary stimulus will probably come sooner than previously expected.

The second, more notable, leg of the sell-off was triggered around 2:45 PM by Bernanke's response to a reporter's question about the sell-off in the Treasury market over the past several weeks that has sent bond yields soaring.

Bernanke said, "Yes, rates have come up some. That's in part due to more optimism – I think – about the economy. It's in part due to perceptions of the Federal Reserve. The forecasts that our participants submitted for this meeting, of course, were done in the last few days, so they were done with full knowledge of what happened to financial conditions. Rates have tightened some, but other factors have been more positive – increasing house prices, for example."

Then, Bernanke concluded, "If interest rates go up for the right reasons – that is, both optimism about the economy and an accurate assessment of monetary policy – that's a good thing. That's not a bad thing."